A number of protein kinases have already proved to be suitable target molecules for therapeutic intervention in a variety of indications, e.g. cancer and inflammatory and autoimmune diseases. Since a high percentage of the genes involved in the development of cancer which have been identified thus far encode kinases, these enzymes are attractive target molecules for the therapy of cancer in particular.
The phosphoinositide 3-kinase (PI3K) pathway is activated in a broad spectrum of human cancers. This may occur either via mutation of PI3K resulting in activation of the kinase, or indirectly via inactivation of the phosphotase and tensin homologue (PTEN) suppressor. In both cases, an activation of the signalling cascade is induced that promotes transformation of cells both in vitro and in vivo. Within the cascade, the Pi3K family of enzymes and the kinase mTOR play a pivotal role. The PI3K family comprises 15 lipid kinases with distinct substrate specificities, expression pattern and modes of regulation. They play an important role in numerous cell processes such as e.g. cell growth and differentiation processes, the control of cytoskeletal changes and the regulation of intracellular transport processes. On the basis of their in vitro specificity for certain phosphoinositide substrates the PI3-kinases can be divided into different categories. The mammalian target of rapamycin (mTOR) is a serine/threonine kinase related to the lipide kinases of the PI3-kinase family. It exists in two complexes, mTORC1 and mTORC2, which are differentially regulated, have distinct substrate specificities, and are differentially sensitive to rapamycin. The central role of mTOR in controlling key cellular growth and survival pathways has sparked interest in discovering mTOR inhibitors that bind to the ATP site and therefore target both mTORC2 and mTORC1. As a consequence, inhibition of the PI3K pathway, particularly mediated via Pi3Kα and mTOR, has emerged as an attractive target for cancer therapeutics.
5-Alkynyl-pyrimidines are described for example as protein kinases inhibiting compounds in WO2006044823.